Biomedical subjects

Andrew V Oleinikov

Publications and source records attributed to Andrew V Oleinikov.

4 recordsLinked to original sources

PubMed2005

RNA interference by mixtures of siRNAs prepared using custom oligonucleotide arrays.

RNA interference (RNAi) is a process in which double-strand RNA (dsRNA) directs the specific degradation of a corresponding target mRNA. The mediators of this process are small dsRNAs, of approximately 21 bp in length, called small interfering RNAs (siRNAs). siRNAs, which can be prepared in vitro in a number of ways and then transfected into cells, can direct the degradation of corresponding mRNAs inside these cells. Hence, siRNAs represent a powerful tool for studying gene functions, as well as having the potential of being highly specific pharmaceutical agents. Some limitations in using this technology exist because the preparation of siRNA in vitro and screening for siRNAs efficient in RNAi can be expensive and time-consuming processes. Here, we demonstrate that custom oligonucleotide arrays can be efficiently used for the preparation of defined mixtures of siRNAs for the silencing of exogenous and endogenous genes. The method is fast, inexpensive, does not require siRNA optimization and has a number of advantages over methods utilizing enzymatic preparation of siRNAs by digestion of longer dsRNAs, as well as methods based on chemical synthesis of individual siRNAs or their DNA templates.

Green Fluorescent Proteins↗

PubMed2004

The adaptor disabled-2 binds to the third psi xNPxY sequence on the cytoplasmic tail of megalin.

The cytoplasmic tail (CT) of megalin possesses several functional motifs likely to participate in protein-protein interactions within the proximal tubular epithelial cell (PTEC) of the kidney. One such interaction is with the phosphotyrosine interaction domain (PID) of the adaptor protein disabled-2 (Dab2), a mitogen-responsive phosphoprotein, which interacts via its PID with Psi xNPxY (where Psi represents a hydrophobic residue) motifs on its binding partners. Megalin CT has three such motifs; it has been established that there is no interaction of Dab2 with the first (from N to C) (Biochem. J. 3 (2000) 613). Here, we analyse in real-time the binding of recombinant megalin CT, and of synthetic peptide sequences encompassing the second and third Psi xNPxY motifs, to Dab2PID in real-time using surface plasmon resonance (SPR). We report a binding affinity of DabPID for megalin CT of K(D) = 2.6 x 10(-7) +/- 5.3 x 10(-8). Direct binding and competition studies indicate that this interaction is with the third Psi xNPxY motif. The dissociation of Dab2 from the third Psi xNPxY peptide was significantly slower than that from the second (k(off) (mean +/- S.E.M.) (per s) = 0.002 +/- 0.002 vs. 0.007 +/- 0.002, P < 0.05). Synthetic peptide sequences encompassing the third Psi xNPxY but not the second inhibited Dab2PID binding both to intact megalin CT and to the third Psi xNPxY motif. Tyrosine phosphorylation of either motif did not exert a major effect upon competition efficacy. We further demonstrate for the first time the presence of Dab2 expression in primary human PTEC.

Adaptor Proteins, Signal Transducing↗

PubMed2000

A small N-terminal 60-kD fragment of gp600 (megalin), the major autoantigen of active Heymann nephritis, can induce a full-blown disease.

Active Heymann nephritis of rat, an autoimmune glomerular disease, is an immunohistological, ultrastructural, and clinical model of human membranous glomerulonephritis. Both diseases in their full-blown form are characterized by (1) the formation of large, subepithelial glomerular immune deposits, which stain for IgG, C3, and membrane attack (C5b-9) components of complement and (2) the excretion of large amounts of protein in the urine (proteinuria). The target autoantigen of active Heymann nephritis is a large transmembrane renal glycoprotein with a molecular weight of approximately 600 kD, variously named gp600, gp330, LRP-2, or "megalin." This study was performed to identify the region in this enormously large glycoprotein that would produce full-blown active Heymann nephritis. A stable, small (60-kD) proteolytic fragment of gp600 was isolated and localized to the N-terminal end of the molecule using Western blot, sequencing, and amino acid analyses. Based on its primary structure, this fragment contains approximately 60 cysteine residues, the cross-linking of which to each other probably explains its stability. Immunization of rats with this fragment induced a full-blown disease that was comparable to the disease induced by a preparation containing the whole protein. These results indicate that this small fragment, retaining the natural disulfide bonds and probably its overall structure, contains those B and T cell epitopes that are sufficient to produce this organ-specific autoimmune disease.

Animals↗

PubMedDate not supplied

Self-assembling protein arrays using electronic semiconductor microchips and in vitro translation.

Protein arrays will greatly accelerate research and development in medical and biological sciences. We have used cell-free protein biosynthesis and a parallel immobilization strategy for producing protein biochips. We demonstrate a model two-protein microarray using luciferase and green fluorescent protein, both expressed in a cell-free system and specifically immobilized on CombiMatrix semiconductor oligonucleotide microarrays. This demonstration provides evidence for the appropriate folding, activity, robust presentation, and efficient flexible detection of proteins on the microscale.

Fluorescent Antibody Technique, Indirect↗